sys/kern/kern_acct.c

   1 /*-
   2  * Copyright (c) 1994 Christopher G. Demetriou
   3  * Copyright (c) 1982, 1986, 1989, 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  * (c) UNIX System Laboratories, Inc.
   6  * All or some portions of this file are derived from material licensed
   7  * to the University of California by American Telephone and Telegraph
   8  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   9  * the permission of UNIX System Laboratories, Inc.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. All advertising materials mentioning features or use of this software
  20  *    must display the following acknowledgement:
  21  *      This product includes software developed by the University of
  22  *      California, Berkeley and its contributors.
  23  * 4. Neither the name of the University nor the names of its contributors
  24  *    may be used to endorse or promote products derived from this software
  25  *    without specific prior written permission.
  26  *
  27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  37  * SUCH DAMAGE.
  38  *
  39  *      @(#)kern_acct.c 8.1 (Berkeley) 6/14/93
  40  * $FreeBSD: src/sys/kern/kern_acct.c,v 1.23.2.1 2002/07/24 18:33:55 johan Exp $
  41  * $DragonFly: src/sys/kern/kern_acct.c,v 1.28 2008/05/08 01:26:00 dillon Exp $
  42  */
  43
  44 #include <sys/param.h>
  45 #include <sys/systm.h>
  46 #include <sys/sysproto.h>
  47 #include <sys/proc.h>
  48 #include <sys/priv.h>
  49 #include <sys/mount.h>
  50 #include <sys/vnode.h>
  51 #include <sys/fcntl.h>
  52 #include <sys/syslog.h>
  53 #include <sys/kernel.h>
  54 #include <sys/sysent.h>
  55 #include <sys/sysctl.h>
  56 #include <sys/nlookup.h>
  57 #include <sys/acct.h>
  58 #include <sys/resourcevar.h>
  59 #include <sys/tty.h>
  60
  61 #include <vm/vm_zone.h>
  62
  63 #include <sys/mplock2.h>
  64
  65 /*
  66  * The routines implemented in this file are described in:
  67  *      Leffler, et al.: The Design and Implementation of the 4.3BSD
  68  *          UNIX Operating System (Addison Welley, 1989)
  69  * on pages 62-63.
  70  *
  71  * Arguably, to simplify accounting operations, this mechanism should
  72  * be replaced by one in which an accounting log file (similar to /dev/klog)
  73  * is read by a user process, etc.  However, that has its own problems.
  74  */
  75
  76 /*
  77  * Internal accounting functions.
  78  * The former's operation is described in Leffler, et al., and the latter
  79  * was provided by UCB with the 4.4BSD-Lite release
  80  */
  81 static comp_t   encode_comp_t (u_long, u_long);
  82 static void     acctwatch (void *);
  83
  84 /*
  85  * Accounting callout handle used for periodic scheduling of
  86  * acctwatch.
  87  */
  88 static struct   callout acctwatch_handle;
  89
  90 /*
  91  * Accounting vnode pointer, and saved vnode pointer.
  92  */
  93 static struct   vnode *acctp;
  94 static struct   vnode *savacctp;
  95
  96 /*
  97  * Values associated with enabling and disabling accounting
  98  */
  99 static int acctsuspend = 2;     /* stop accounting when < 2% free space left */
 100 SYSCTL_INT(_kern, OID_AUTO, acct_suspend, CTLFLAG_RW,
 101         &acctsuspend, 0, "Percentage of free disk space below which accounting will be suspended");
 102
 103 static int acctresume = 4;      /* resume when free space risen to > 4% */
 104 SYSCTL_INT(_kern, OID_AUTO, acct_resume, CTLFLAG_RW,
 105         &acctresume, 0, "Minimum percentage of free disk space needed to resume accounting");
 106
 107 static int acctchkfreq = 15;    /* frequency (in seconds) to check space */
 108 SYSCTL_INT(_kern, OID_AUTO, acct_chkfreq, CTLFLAG_RW,
 109         &acctchkfreq, 0, "Frequency (in seconds) of free disk space checking");
 110
 111 static void
 112 acct_init(void *arg __unused)
 113 {
 114         callout_init(&acctwatch_handle);
 115 }
 116 SYSINIT(acct, SI_SUB_DRIVERS, SI_ORDER_ANY, acct_init, NULL);
 117
 118 /*
 119  * Accounting system call.  Written based on the specification and
 120  * previous implementation done by Mark Tinguely.
 121  *
 122  * acct(char *path)
 123  *
 124  * MPALMOSTSAFE
 125  */
 126 int
 127 sys_acct(struct acct_args *uap)
 128 {
 129         struct thread *td = curthread;
 130         struct nlookupdata nd;
 131         struct vnode *vp;
 132         int error;
 133
 134         error = priv_check(td, PRIV_ACCT);
 135         if (error)
 136                 return (error);
 137
 138         get_mplock();
 139
 140         /*
 141          * If accounting is to be started to a file, open that file for
 142          * appending and make sure it's a 'normal'.
 143          */
 144         if (uap->path != NULL) {
 145                 error = nlookup_init(&nd, uap->path, UIO_USERSPACE,
 146                                         NLC_LOCKVP);
 147                 if (error == 0)
 148                         error = vn_open(&nd, NULL, FWRITE | O_APPEND, 0);
 149                 if (error == 0 && nd.nl_open_vp->v_type != VREG)
 150                         error = EACCES;
 151                 if (error) {
 152                         nlookup_done(&nd);
 153                         goto done;
 154                 }
 155                 vp = nd.nl_open_vp;
 156                 nd.nl_open_vp = NULL;
 157                 nlookup_done(&nd);
 158
 159                 vn_unlock(vp);
 160         } else {
 161                 vp = NULL;
 162         }
 163
 164         /*
 165          * If accounting was previously enabled, kill the old space-watcher,
 166          * close the file.
 167          */
 168         if (acctp != NULLVP || savacctp != NULLVP) {
 169                 callout_stop(&acctwatch_handle);
 170                 error = vn_close((acctp != NULLVP ? acctp : savacctp),
 171                                 FWRITE | O_APPEND);
 172                 acctp = savacctp = NULLVP;
 173         }
 174
 175         /*
 176          * If no new file opened then leave.  We never did an nlookup so
 177          * don't try cleaning it up.
 178          */
 179         if (uap->path == NULL)
 180                 goto done;
 181
 182         /*
 183          * Save the new accounting file vnode, and schedule the new
 184          * free space watcher.
 185          */
 186         acctp = vp;
 187         acctwatch(NULL);
 188 done:
 189         rel_mplock();
 190         return (error);
 191 }
 192
 193 /*
 194  * Write out process accounting information, on process exit.
 195  * Data to be written out is specified in Leffler, et al.
 196  * and are enumerated below.  (They're also noted in the system
 197  * "acct.h" header file.)
 198  */
 199
 200 int
 201 acct_process(struct proc *p)
 202 {
 203         struct acct acct;
 204         struct rusage *r;
 205         struct rusage ru;
 206         struct timeval tmp;
 207         struct rlimit rlim;
 208         int t;
 209         struct vnode *vp;
 210
 211         /* If accounting isn't enabled, don't bother */
 212         vp = acctp;
 213         if (vp == NULLVP)
 214                 return (0);
 215
 216         /*
 217          * Get process accounting information.
 218          */
 219
 220         /* (1) The name of the command that ran */
 221         bcopy(p->p_comm, acct.ac_comm, sizeof acct.ac_comm);
 222
 223         /* (2) The amount of user and system time that was used */
 224         calcru_proc(p, &ru);
 225         acct.ac_utime = encode_comp_t(ru.ru_utime.tv_sec, ru.ru_utime.tv_usec);
 226         acct.ac_stime = encode_comp_t(ru.ru_stime.tv_sec, ru.ru_stime.tv_usec);
 227
 228         /* (3) The elapsed time the commmand ran (and its starting time) */
 229         acct.ac_btime = p->p_start.tv_sec;
 230         microtime(&tmp);
 231         timevalsub(&tmp, &p->p_start);
 232         acct.ac_etime = encode_comp_t(tmp.tv_sec, tmp.tv_usec);
 233
 234         /* (4) The average amount of memory used */
 235         r = &p->p_ru;
 236         tmp = ru.ru_utime;;
 237         timevaladd(&tmp, &ru.ru_stime);
 238         t = tmp.tv_sec * hz + tmp.tv_usec / ustick;
 239         if (t)
 240                 acct.ac_mem = (r->ru_ixrss + r->ru_idrss + r->ru_isrss) / t;
 241         else
 242                 acct.ac_mem = 0;
 243
 244         /* (5) The number of disk I/O operations done */
 245         acct.ac_io = encode_comp_t(r->ru_inblock + r->ru_oublock, 0);
 246
 247         /* (6) The UID and GID of the process */
 248         acct.ac_uid = p->p_ucred->cr_ruid;
 249         acct.ac_gid = p->p_ucred->cr_rgid;
 250
 251         /* (7) The terminal from which the process was started */
 252         if ((p->p_flag & P_CONTROLT) && p->p_pgrp->pg_session->s_ttyp)
 253                 acct.ac_tty = dev2udev(p->p_pgrp->pg_session->s_ttyp->t_dev);
 254         else
 255                 acct.ac_tty = NOUDEV;
 256
 257         /* (8) The boolean flags that tell how the process terminated, etc. */
 258         acct.ac_flag = p->p_acflag;
 259
 260         /*
 261          * Eliminate any file size rlimit.
 262          */
 263         rlim.rlim_cur = RLIM_INFINITY;
 264         rlim.rlim_max = RLIM_INFINITY;
 265         plimit_modify(p, RLIMIT_FSIZE, &rlim);
 266
 267         /*
 268          * Write the accounting information to the file.
 269          */
 270         return (vn_rdwr(UIO_WRITE, vp, (caddr_t)&acct, sizeof (acct),
 271             (off_t)0, UIO_SYSSPACE, IO_APPEND|IO_UNIT, p->p_ucred,
 272             NULL));
 273 }
 274
 275 /*
 276  * Encode_comp_t converts from ticks in seconds and microseconds
 277  * to ticks in 1/AHZ seconds.  The encoding is described in
 278  * Leffler, et al., on page 63.
 279  */
 280
 281 #define MANTSIZE        13                      /* 13 bit mantissa. */
 282 #define EXPSIZE         3                       /* Base 8 (3 bit) exponent. */
 283 #define MAXFRACT        ((1 << MANTSIZE) - 1)   /* Maximum fractional value. */
 284
 285 static comp_t
 286 encode_comp_t(u_long s, u_long us)
 287 {
 288         int exp, rnd;
 289
 290         exp = 0;
 291         rnd = 0;
 292         s *= AHZ;
 293         s += us / (1000000 / AHZ);      /* Maximize precision. */
 294
 295         while (s > MAXFRACT) {
 296         rnd = s & (1 << (EXPSIZE - 1)); /* Round up? */
 297                 s >>= EXPSIZE;          /* Base 8 exponent == 3 bit shift. */
 298                 exp++;
 299         }
 300
 301         /* If we need to round up, do it (and handle overflow correctly). */
 302         if (rnd && (++s > MAXFRACT)) {
 303                 s >>= EXPSIZE;
 304                 exp++;
 305         }
 306
 307         /* Clean it up and polish it off. */
 308         exp <<= MANTSIZE;               /* Shift the exponent into place */
 309         exp += s;                       /* and add on the mantissa. */
 310         return (exp);
 311 }
 312
 313 /*
 314  * Periodically check the file system to see if accounting
 315  * should be turned on or off.  Beware the case where the vnode
 316  * has been vgone()'d out from underneath us, e.g. when the file
 317  * system containing the accounting file has been forcibly unmounted.
 318  */
 319 /* ARGSUSED */
 320 static void
 321 acctwatch(void *a)
 322 {
 323         struct statfs sb;
 324
 325         if (savacctp != NULLVP) {
 326                 if (savacctp->v_type == VBAD) {
 327                         (void) vn_close(savacctp, FWRITE | O_APPEND);
 328                         savacctp = NULLVP;
 329                         return;
 330                 }
 331                 (void)VFS_STATFS(savacctp->v_mount, &sb, proc0.p_ucred);
 332                 if (sb.f_bavail > acctresume * sb.f_blocks / 100) {
 333                         acctp = savacctp;
 334                         savacctp = NULLVP;
 335                         log(LOG_NOTICE, "Accounting resumed\n");
 336                 }
 337         } else {
 338                 if (acctp == NULLVP)
 339                         return;
 340                 if (acctp->v_type == VBAD) {
 341                         (void) vn_close(acctp, FWRITE | O_APPEND);
 342                         acctp = NULLVP;
 343                         return;
 344                 }
 345                 (void)VFS_STATFS(acctp->v_mount, &sb, proc0.p_ucred);
 346                 if (sb.f_bavail <= acctsuspend * sb.f_blocks / 100) {
 347                         savacctp = acctp;
 348                         acctp = NULLVP;
 349                         log(LOG_NOTICE, "Accounting suspended\n");
 350                 }
 351         }
 352         callout_reset(&acctwatch_handle, acctchkfreq * hz, acctwatch, NULL);
 353 }